Stable chloroplast transformation in potato: use of green fluorescent protein as a plastid marker

We describe here the development of a reproducible plastid transformation s ystem for potato and regeneration of plants with uniformly transformed plas tids. Two distinct tobacco-specific plastid vectors, pZS197 (Prrn/aadA/Tpsb A) and pMON30125 (Prrn/GFP/Trps16::PpsbA/aadA/TpsbA), designed for integrat ion into the large single copy and inverted repeat regions of the plastid g enome, respectively, were bombarded into leaf explants of potato line FL160 7. A total of three transgenic lines were selected out of 46 plates bombard ed with pZS197 and three transgenic lines out of 104 plates were obtained w ith pMON30125. Development of a high frequency leaf-based regeneration syst em, a stringent selection scheme and optimization of biolistic transformati on protocol were critical for recovery of plastid transformants. Plastid-ex pressed green fluorescent protein was used as a visual marker for identific ation of plastid transformants at the early stage of selection and shoot re generation. The establishment of a plastid transformation system in potato, which has several advantages over routinely used nuclear transformation, o ffers new possibilities for genetic improvement of this crop.